Scientists were excavating a site in Laetoli, Tanzania when they uncovered two new sets of hominin tracks located about 150 meters south of the tracks found by Mary Leakey in the 1970’s. They estimated the heights of the two individuals using the size and shape of the footprints.

In this study, scientists compared two populations of pregnant mice, one which was kept germ-free throughout pregnancy and the other which was exposed during pregnancy to a strain of E. coli to determine whether the immune systems of offspring begin to develop in utero. Worksheets also available in Spanish.

Researchers investigated the role of p53 in cell cycle regulation by genetically engineering cell lines with disrupted alleles of the p53 gene. They exposed the cell lines to DNA-damaging radiation and observed how this exposure impacted mitosis.

Scientists collected bacteria from locations that had never been exposed to humans or modern antibiotics to determine if antibiotic resistance is newly evolved since the introduction of antibiotics or has evolved independently.